Mice end up confined to a particular area (7)
I believe the answer is:
endemic
'confined to a particular area' is the definition.
(I've seen this before)
'mice end up' is the wordplay.
'up' indicates an anagram (letters get chucked up).
'mice'+'end'='miceend'
'miceend' with letters rearranged gives 'ENDEMIC'.
(Other definitions for endemic that I've seen before include "(Of disease) regularly found in population" , "Peculiar to local area" , "Restricted to a certain area" , "in the vicinity" , "Only found in a particular region, or regions" .)